---
res:
  bibo_abstract:
  - Power semiconductor modules are used to control and switch high electrical currents
    and voltages. Within the power module package wire bonding is used as an interconnection
    technology. In recent years, aluminum wire has been used preferably, but an ever-growing
    market of powerful and efficient power modules requires a material with better
    mechanical and electrical properties. For this reason, a technology change from
    aluminum to copper is indispensable. However, the copper wire bonding process
    reacts more sensitive to parameter changes. This makes manufacturing reliable
    copper bond connections a challenging task. The aim of the BMBF funded project
    Itsowl-InCuB is the development of self-optimizing techniques to enable the reliable
    production of copper bond connections under varying conditions. A model of the
    process is essential to achieve this aim. This model needs to include the dynamic
    elasto-plastic deformation, the ultrasonic softening effect and the proceeding
    adhesion between wire and substrate. This paper focusses on the pre-deformation
    process. In the touchdown phase, the wire is pressed into the V-groove of the
    tool and a small initial contact area between wire and substrate arise. The local
    characteristics of the material change abruptly because of the cold forming. Consequently,
    the pre-deformation has a strong effect on the joining process. In [1], a pre-cleaning
    effect during the touchdown process of aluminum wires by cracking of oxide layers
    was presented. These interactions of the process parameters are still largely
    unknown for copper. In a first step, this paper validates the importance of modeling
    the pre-deformation by showing its impact on the wire deformation characteristic
    experimentally. Creating cross-section views of pre-deformed copper wires has
    shown a low deformation degree compared to aluminum. By using a digital microscope
    and a scanning confocal microscope an analysis about the contact areas and penetration
    depths after touchdown has been made. Additionally, it has to be taken into account
    that the dynamical touchdown force depends on the touchdown speed and the touchdown
    force set in the bonding machine. In order to measure the overshoot in the force
    signals, a strain gauge sensor has been used. Subsequently, the affecting factors
    have been interpreted independently Furthermore, the material properties of copper
    wire have been investigated with tensile tests and hardness measurements. In a
    second step, the paper presents finite element models of the touchdown process
    for source and destination bonds. These models take the measured overshoot in
    the touchdown forces into account. A multi-linear, isotropic material model has
    been selected to map the material properties of the copper. A validation of the
    model with the experimental determined contact areas, normal pressures and penetration
    depths reveals the high model quality. Thus, the simulation is able to calculate
    and visualize the three dimensional pre-deformation with an integrated material
    parameter of the wire if the touchdown parameters of the bonding machine are known.
    Based on the calculated deformation degrees of wire and substrate, it is probably
    possible to investigate the effect of the pre-deformation on the pre-cleaning
    phase in the copper wire bonding.@eng
  bibo_authorlist:
  - foaf_Person:
      foaf_givenName: Andreas
      foaf_name: Unger, Andreas
      foaf_surname: Unger
  - foaf_Person:
      foaf_givenName: Walter
      foaf_name: Sextro, Walter
      foaf_surname: Sextro
      foaf_workInfoHomepage: http://www.librecat.org/personId=21220
  - foaf_Person:
      foaf_givenName: Simon
      foaf_name: Althoff, Simon
      foaf_surname: Althoff
  - foaf_Person:
      foaf_givenName: Paul
      foaf_name: Eichwald, Paul
      foaf_surname: Eichwald
  - foaf_Person:
      foaf_givenName: Tobias
      foaf_name: Meyer, Tobias
      foaf_surname: Meyer
  - foaf_Person:
      foaf_givenName: Florian
      foaf_name: Eacock, Florian
      foaf_surname: Eacock
  - foaf_Person:
      foaf_givenName: Michael
      foaf_name: Brökelmann, Michael
      foaf_surname: Brökelmann
  dct_date: 2014^xs_gYear
  dct_language: eng
  dct_subject:
  - pre-deformation
  - copper wire bonding
  - finite element model
  dct_title: Experimental and Numerical Simulation Study of Pre-Deformed Heavy Copper
    Wire Wedge Bonds@
...